Genetic, biochemical and biophysical methods will be used to identify the intermediate steps in bacterial transformation, characterize the deoxyribonucleate (DNA) structure of the unreplicated products of bacteriophage lambda recombination, investigate the role of branch migration in the formation of bacteriophage lambda recombinants, investigate the role of mismatch repair in fine structure recombination and investigate the role of a mismatch recognizing function in bacterial mutagenesis.